Cooling consumes a large part of energy expenditures for data centers. The goal of conserving energy creates a need to allocate cooling within a data center as efficiently as possible. Today, the use of economizers in the cooling of IT spaces is limited to times where outside weather conditions allow the HVAC system to bring the temperature of the IT space down to a static temperature set point of the space, which may be set at 68° F. (20° C.). The function of an economizer in an HVAC system is to “economize” or save on the cost of cooling a space. Because operating a compressor is so energy intensive, the ability to cool an indoor space without running the compressor can provide significant cost savings. Unfortunately, an economizer can only be used when the outdoor temperature and humidity is low enough that the HVAC system can supply air to the space at or near the system's temperature set point.
IT spaces, for the most part, are cooled to a static set point. As mentioned above, a typical temperature set point for an IT space is at or near 68° F. (20° C.). Keeping IT equipment at this temperature over the course of its life, according to the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), keeps the rate of IT equipment failure at a “baseline” level. For HVAC engineers, this means that an economizer, in today's systems, can only be utilized when the outdoor conditions allow the system to achieve a temperature at or about the 68° F. (20° C.) set point. Thus, for many temperate climates, economizer usage is, at worst, seasonal and, at best, sparse during spring, summer and fall months.